package com.zlkj.weixin.kit;
import java.io.StringReader;
import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.util.Arrays;
import java.util.Random;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.apache.commons.codec.binary.Base64;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.InputSource;

import com.zlkj.weixin.utils.ByteGroup;
import com.zlkj.weixin.utils.PKCS7Encoder;
import com.zlkj.weixin.utils.WeiXinFinalValue;
/**
 * 微信Servlet web层
 * @author 程序媛
 * QQ群 群1： 494705674 群2:605806884
 */
public class WeiXinSecurityKit {
	 private static final Base64 base64 = new Base64();
	  private static final Charset CHARSET = Charset.forName("utf-8");

	  private static final ThreadLocal<DocumentBuilder> builderLocal = new ThreadLocal<DocumentBuilder>() {
	    @Override
	    protected DocumentBuilder initialValue() {
	      try {
	        return DocumentBuilderFactory.newInstance().newDocumentBuilder();
	      } catch (ParserConfigurationException exc) {
	        throw new IllegalArgumentException(exc);
	      }
	    }
	  };
	
	public static String shal(String str)throws Exception{
		StringBuffer buffer=null;
	try {
		 buffer=new StringBuffer();
			MessageDigest messageDigest=MessageDigest.getInstance("sha1");
			messageDigest.update(str.getBytes());
		for(byte bs:messageDigest.digest()){
			buffer.append(String.format("%02x",bs));
		}
		return buffer.toString();
	} catch (Exception e) {
		e.printStackTrace();
		return null;
	}
}
	
	public static String shal(String... arr){
		String[] arrs=arr;
		StringBuffer buffer=null;
	try {
		  Arrays.sort(arrs);
		  buffer=new StringBuffer();
		    for (String a : arrs) {
		    	buffer.append(a);
		    }
		    return shal(buffer.toString());
	} catch (Exception e) {
		e.printStackTrace();
		return null;
	}
}
	
	/**
	 * js接口签名校验
	 * @param jsapi_ticket
	 * @param timestamp
	 * @param noncestr
	 * @param url
	 * @return
	 * @throws Exception
	 */
	public  static String jssdkSignature(String jsapi_ticket, String timestamp, String noncestr, String url) throws Exception {
		jsapi_ticket = "jsapi_ticket=" + jsapi_ticket;
		noncestr = "noncestr=" + noncestr;
		timestamp = "timestamp=" + timestamp;
		url = "url=" + url;
		String arrys[]=new String[]{jsapi_ticket,noncestr,timestamp,url};
			Arrays.asList(arrys);
			StringBuffer buffer=new StringBuffer();
			for(int i=0;i<arrys.length;i++){
				buffer.append(arrys[i]);
				if(i!=arrys.length-1)
					buffer.append("&");
			}
			return shal(buffer.toString());
	}
	
	
	/**
	   * 构造函数
	   *
	   * @param token           公众平台上，开发者设置的token
	   * @param encodingAesKey  公众平台上，开发者设置的EncodingAESKey
	   * @param appidOrCorpid          公众平台appid/corpid
	   */

	  static String extractEncryptPart(String xml) {
	    try {
	      DocumentBuilder db = builderLocal.get();
	      Document document = db.parse(new InputSource(new StringReader(xml)));

	      Element root = document.getDocumentElement();
	      return root.getElementsByTagName("Encrypt").item(0).getTextContent();
	    } catch (Exception e) {
	      throw new RuntimeException(e);
	    }
	  }

	  /**
	   * 将公众平台回复用户的消息加密打包.
	   * <ol>
	   * <li>对要发送的消息进行AES-CBC加密</li>
	   * <li>生成安全签名</li>
	   * <li>将消息密文和安全签名打包成xml格式</li>
	   * </ol>
	   *
	   * @param plainText 公众平台待回复用户的消息，xml格式的字符串
	   * @return 加密后的可以直接回复用户的密文，包括msg_signature, timestamp, nonce, encrypt的xml格式的字符串
	   */
	  public String encrypt(String plainText) {
	    // 加密
	    String encryptedXml = encrypt(genRandomStr(), plainText);

	    // 生成安全签名
	    String timeStamp = Long.toString(System.currentTimeMillis() / 1000l);
	    String nonce = genRandomStr();

	    String signature = WeiXinSecurityKit.shal(WeiXinFinalValue.TOKEN, timeStamp, nonce, encryptedXml);
	    String result = generateXml(encryptedXml, signature, timeStamp, nonce);
	    return result;
	  }

	  /**
	   * 对明文进行加密.
	   *
	   * @param plainText 需要加密的明文
	   * @return 加密后base64编码的字符串
	   */
	  protected String encrypt(String randomStr, String plainText) {
	    ByteGroup byteCollector = new ByteGroup();
	    byte[] randomStringBytes = randomStr.getBytes(CHARSET);
	    byte[] plainTextBytes = plainText.getBytes(CHARSET);
	    byte[] bytesOfSizeInNetworkOrder = number2BytesInNetworkOrder(
	            plainTextBytes.length);
	    byte[] appIdBytes = WeiXinFinalValue.APPID.getBytes(CHARSET);

	    // randomStr + networkBytesOrder + text + appid
	    byteCollector.addBytes(randomStringBytes);
	    byteCollector.addBytes(bytesOfSizeInNetworkOrder);
	    byteCollector.addBytes(plainTextBytes);
	    byteCollector.addBytes(appIdBytes);

	    // ... + pad: 使用自定义的填充方式对明文进行补位填充
	    byte[] padBytes = PKCS7Encoder.encode(byteCollector.size());
	    byteCollector.addBytes(padBytes);

	    // 获得最终的字节流, 未加密
	    byte[] unencrypted = byteCollector.toBytes();

	    try {
	      // 设置加密模式为AES的CBC模式
	      Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
	      SecretKeySpec keySpec = new SecretKeySpec(Base64.decodeBase64(WeiXinFinalValue.AESKEY + "="), "AES");
	      IvParameterSpec iv = new IvParameterSpec(Base64.decodeBase64(WeiXinFinalValue.AESKEY + "="), 0, 16);
	      cipher.init(Cipher.ENCRYPT_MODE, keySpec, iv);

	      // 加密
	      byte[] encrypted = cipher.doFinal(unencrypted);

	      // 使用BASE64对加密后的字符串进行编码
	      String base64Encrypted = base64.encodeToString(encrypted);

	      return base64Encrypted;
	    } catch (Exception e) {
	      throw new RuntimeException(e);
	    }
	  }

	  /**
	   * 检验消息的真实性，并且获取解密后的明文.
	   * <ol>
	   * <li>利用收到的密文生成安全签名，进行签名验证</li>
	   * <li>若验证通过，则提取xml中的加密消息</li>
	   * <li>对消息进行解密</li>
	   * </ol>
	   * @param msgSignature 签名串，对应URL参数的msg_signature
	   * @param timeStamp    时间戳，对应URL参数的timestamp
	   * @param nonce        随机串，对应URL参数的nonce
	   * @param encryptedXml 密文，对应POST请求的数据
	   * @return 解密后的原文
	   */
	  public static String decrypt(String msgSignature, String timeStamp, String nonce,
	                        String encryptedXml) {
	    // 密钥，公众账号的app corpSecret
	    // 提取密文
	    String cipherText = extractEncryptPart(encryptedXml);

	    // 验证安全签名
	    String signature = WeiXinSecurityKit.shal(WeiXinFinalValue.TOKEN, timeStamp, nonce, cipherText);
	    if (!signature.equals(msgSignature)) {
	      throw new RuntimeException("加密消息签名校验失败");
	    }

	    // 解密
	    String result = decrypt(cipherText);
	    return result;
	  }

	  /**
	   * 对密文进行解密.
	   *异常  
	   * @param cipherText 需要解密的密文
	   * @return 解密得到的明文
	   */
	  public  static String decrypt(String cipherText) {
	    byte[] original;
	    try {
	      // 设置解密模式为AES的CBC模式
	      Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
	      SecretKeySpec key_spec = new SecretKeySpec(Base64.decodeBase64(WeiXinFinalValue.AESKEY + "="), "AES");
	      IvParameterSpec iv = new IvParameterSpec(
	              Arrays.copyOfRange(Base64.decodeBase64(WeiXinFinalValue.AESKEY + "="), 0, 16));
	      cipher.init(Cipher.DECRYPT_MODE, key_spec, iv);

	      // 使用BASE64对密文进行解码
	      byte[] encrypted = Base64.decodeBase64(cipherText);

	      // 解密
	      original = cipher.doFinal(encrypted);
	    } catch (Exception e) {
	    	/**
	    	 * java.lang.RuntimeException: java.security.InvalidKeyException: Illegal key size 异常  
	    	 * 异常分析：
	    	 * 使用AES加密时，当密钥大于128时，代码会抛出java.security.InvalidKeyException: Illegal key size or default parameters
			 * Illegal key size or default parameters是指密钥长度是受限制的，java运行时环境读到的是受限的policy文件。文件位于${java_home}/jre/lib/security
			 * 这种限制是因为美国对软件出口的控制。
	    	 * 解决方案:
	    	 * 		解压 WebRoot 下的UnlimitedJCEPolicyJDK7.zip文件找到local_policy.jar和US_export_policy.jar
	    	 * 		来替换${java_home}/jre/lib/security/ 下面的local_policy.jar和US_export_policy.jar
	    	 */
	      throw new RuntimeException(e);
	    }

	    String xmlContent, from_appid;
	    try {
	      // 去除补位字符
	      byte[] bytes = PKCS7Encoder.decode(original);

	      // 分离16位随机字符串,网络字节序和AppId
	      byte[] networkOrder = Arrays.copyOfRange(bytes, 16, 20);

	      int xmlLength = bytesNetworkOrder2Number(networkOrder);

	      xmlContent = new String(Arrays.copyOfRange(bytes, 20, 20 + xmlLength),
	              CHARSET);
	      from_appid = new String(
	              Arrays.copyOfRange(bytes, 20 + xmlLength, bytes.length), CHARSET);
	    } catch (Exception e) {
	      throw new RuntimeException(e);
	    }
	    if (!from_appid.equals(WeiXinFinalValue.APPID)) {// appid不相同的情况
	      throw new RuntimeException("AppID不正确");
	    }
	    return xmlContent;

	  }

	  /**
	   * 将一个数字转换成生成4个字节的网络字节序bytes数组
	   *
	   * @param number
	   */
	  private static byte[] number2BytesInNetworkOrder(int number) {
	    byte[] orderBytes = new byte[4];
	    orderBytes[3] = (byte) (number & 0xFF);
	    orderBytes[2] = (byte) (number >> 8 & 0xFF);
	    orderBytes[1] = (byte) (number >> 16 & 0xFF);
	    orderBytes[0] = (byte) (number >> 24 & 0xFF);
	    return orderBytes;
	  }

	  /**
	   * 4个字节的网络字节序bytes数组还原成一个数字
	   *
	   * @param bytesInNetworkOrder
	   */
	  private static int bytesNetworkOrder2Number(byte[] bytesInNetworkOrder) {
	    int sourceNumber = 0;
	    for (int i = 0; i < 4; i++) {
	      sourceNumber <<= 8;
	      sourceNumber |= bytesInNetworkOrder[i] & 0xff;
	    }
	    return sourceNumber;
	  }

	  /**
	   * 随机生成16位字符串
	   */
	  private static String genRandomStr() {
	    String base = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
	    Random random = new Random();
	    StringBuffer sb = new StringBuffer();
	    for (int i = 0; i < 16; i++) {
	      int number = random.nextInt(base.length());
	      sb.append(base.charAt(number));
	    }
	    return sb.toString();
	  }

	  /**
	   * 生成xml消息
	   *
	   * @param encrypt   加密后的消息密文
	   * @param signature 安全签名
	   * @param timestamp 时间戳
	   * @param nonce     随机字符串
	   * @return 生成的xml字符串
	   */
	  private static String generateXml(String encrypt, String signature,
	      String timestamp, String nonce) {
	    String format = "<xml>\n" + "<Encrypt><![CDATA[%1$s]]></Encrypt>\n"
	            + "<MsgSignature><![CDATA[%2$s]]></MsgSignature>\n"
	            + "<TimeStamp>%3$s</TimeStamp>\n" + "<Nonce><![CDATA[%4$s]]></Nonce>\n"
	            + "</xml>";
	    return String.format(format, encrypt, signature, timestamp, nonce);
	  }
	  public static void main(String[] args) throws Exception {
		System.out.println(shal("jun12258"));
	}
	
}
